1. Field of the Invention
The present invention relates to an image processing device for an endoscope and an endoscope apparatus which perform change of a tone characteristic in accordance with a type or an observation mode of an endoscope image, or an emphasis level for emphasizing sharpness of the endoscope image.
2. Description of the Related Art
An endoscope apparatus is equipped in the function of emphasizing the sharpness of an endoscope image (for example, structure emphasis), and as disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 2004-000335 as the first prior example, switching of an emphasis amount in accordance with an emphasis level is possible by operation of a switch or the like included in the endoscope. Thus, the endoscope images differing in sharpness can be output onto the display device. Further, an endoscope apparatus including special light observation in addition to ordinary light observation, that is, capable of observation with endoscope images of different types by switching the observation mode has also been conceived.
Further, as the method of reducing noise in the low intensity portion of an image, there is, for example, Japanese Patent No. 3540567 as the second prior example applied to an electronic camera. In the second prior art, reduction of noise is realized by specially providing a tone correction circuit for sharpness emphasis processing, which differs in a tone characteristic from that for a main signal.